Throttle control systems and methods for cylinder activation and deactivation

ABSTRACT

An engine control system for a vehicle includes a target torque module that determines a target torque output of an engine based on at least one driver input. A target air per cylinder (APC) module determines a target APC for the engine based on the target torque. A target mass airflow (MAF) module determines a target MAF through a throttle valve of the engine based on the target APC, a number of activated cylinders of the engine, and a total number of cylinders of the engine. A throttle control module determines a target throttle opening based on the target MAF and controls opening of the throttle valve based on the target throttle opening.

FIELD

The present disclosure relates to internal combustion engines and moreparticularly to engine control systems and methods for vehicles.

BACKGROUND

The background description provided here is for the purpose of generallypresenting the context of the disclosure. Work of the presently namedinventors, to the extent it is described in this background section, aswell as aspects of the description that may not otherwise qualify asprior art at the time of filing, are neither expressly nor impliedlyadmitted as prior art against the present disclosure.

Internal combustion engines combust an air and fuel mixture withincylinders to drive pistons, which produces drive torque. Air flow intothe engine is regulated via a throttle. More specifically, the throttleadjusts throttle area, which increases or decreases air flow into theengine. As the throttle area increases, the air flow into the engineincreases. A fuel control system adjusts the rate that fuel is injectedto provide a desired air/fuel mixture to the cylinders and/or to achievea desired torque output. Increasing the amount of air and fuel providedto the cylinders increases the torque output of the engine.

In spark-ignition engines, spark initiates combustion of an air/fuelmixture provided to the cylinders. In compression-ignition engines,compression in the cylinders combusts the air/fuel mixture provided tothe cylinders. Spark timing and air flow may be the primary mechanismsfor adjusting the torque output of spark-ignition engines, while fuelflow may be the primary mechanism for adjusting the torque output ofcompression-ignition engines.

Engine control systems have been developed to control engine outputtorque to achieve a desired torque. Traditional engine control systems,however, do not control the engine output torque as accurately asdesired. Further, traditional engine control systems do not provide arapid response to control signals or coordinate engine torque controlamong various devices that affect the engine output torque.

SUMMARY

An engine control system for a vehicle includes a target torque modulethat determines a target torque output of an engine based on at leastone driver input. A target air per cylinder (APC) module determines atarget APC for the engine based on the target torque. A target massairflow (MAF) module determines a target MAF through a throttle valve ofthe engine based on the target APC, a number of activated cylinders ofthe engine, and a total number of cylinders of the engine. A throttlecontrol module determines a target throttle opening based on the targetMAF and controls opening of the throttle valve based on the targetthrottle opening.

In further features, the target MAF module determines the target MAFfurther based on an APC of the engine, a temperature of air within anintake manifold of the engine, a volumetric efficiency of the engine,and a predetermined response time value.

In still further features, the target MAF module determines the targetMAF using one of a function and a mapping that relates the target APC,the number of activated cylinders, the total number of cylinders, theAPC, the temperature, the volumetric efficiency, and the predeterminedresponse time value to the target MAF.

In yet further features, a second target MAF module determines a secondtarget MAF through the throttle valve based on the target APC, and aselection module selects one of the target MAF and the second target MAFand sets a selected target MAF based on the selected one of the targetMAF and the second target MAF. The throttle control module determinesthe target throttle opening based on the selected target MAF.

In further features, the selection module selects the target MAF when atleast one cylinder of the engine is transitioned from activated todeactivated.

In still further features, the selection module selects the target MAFfor a predetermined period before the at least one cylinder of theengine is transitioned from activated to deactivated.

In yet further features, the selection module selects the target MAFwhen at least one cylinder of the engine is transitioned fromdeactivated to activated.

In further features, the selection module selects the target MAF for apredetermined period before the at least one cylinder of the engine istransitioned from deactivated to activated.

In still further features, the selection module selects the secondtarget MAF when zero cylinders of the engine are transitioned fromdeactivated to activated and zero cylinders of the engine aretransitioned from activated to deactivated.

In yet further features, the throttle control module determines thetarget throttle opening further based on a target intake manifoldpressure.

An engine control method includes: determining a target torque output ofan engine based on at least one driver input; determining a target airper cylinder (APC) for the engine based on the target torque;determining a target mass airflow (MAF) through a throttle valve of theengine based on the target APC, a number of activated cylinders of theengine, and a total number of cylinders of the engine; determining atarget throttle opening based on the target MAF; and controlling openingof the throttle valve based on the target throttle opening.

In further features, the engine control method further includesdetermining the target MAF further based on an APC of the engine, atemperature of air within an intake manifold of the engine, a volumetricefficiency of the engine, and a predetermined response time value.

In still further features, the engine control method further includesdetermining the target MAF using one of a function and a mapping thatrelates the target APC, the number of activated cylinders, the totalnumber of cylinders, the APC, the temperature, the volumetricefficiency, and the predetermined response time value to the target MAF.

In yet further features, the engine control method further includes:determining a second target MAF through the throttle valve based on thetarget APC; selecting one of the target MAF and the second target MAF;setting a selected target MAF based on the selected one of the targetMAF and the second target MAF; and determining the target throttleopening based on the selected target MAF.

In further features, the engine control method further includesselecting the target MAF when at least one cylinder of the engine istransitioned from activated to deactivated.

In still further features, the engine control method further includesselecting the target MAF for a predetermined period before the at leastone cylinder of the engine is transitioned from activated todeactivated.

In yet further features, the engine control method further includesselecting the target MAF when at least one cylinder of the engine istransitioned from deactivated to activated.

In further features, the engine control method further includesselecting the target MAF for a predetermined period before the at leastone cylinder of the engine is transitioned from deactivated toactivated.

In still further features, the engine control method further includesselecting the second target MAF when zero cylinders of the engine aretransitioned from deactivated to activated and zero cylinders of theengine are transitioned from activated to deactivated.

In yet further features, the engine control method further includesdetermining the target throttle opening further based on a target intakemanifold pressure.

Further areas of applicability of the present disclosure will becomeapparent from the detailed description, the claims and the drawings. Thedetailed description and specific examples are intended for purposes ofillustration only and are not intended to limit the scope of thedisclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure will become more fully understood from thedetailed description and the accompanying drawings, wherein:

FIG. 1 is a functional block diagram of an example engine systemaccording to the present disclosure;

FIG. 2 is a functional block diagram of an example engine control systemaccording to the present disclosure;

FIG. 3 is a functional block diagram of an example air control moduleaccording to the present disclosure;

FIG. 4 is a functional block diagram of an example target air percylinder (APC) module according to the present disclosure; and

FIG. 5 includes a flowchart depicting an example method of controlling athrottle valve according to the present disclosure.

In the drawings, reference numbers may be reused to identify similarand/or identical elements.

DETAILED DESCRIPTION

Internal combustion engines combust an air and fuel mixture withincylinders to generate torque. Under some circumstances, an enginecontrol module (ECM) may deactivate one or more cylinders of the engine.The ECM may deactivate one or more cylinders, for example, to decreasefuel consumption when the engine can achieve a torque request using lessthan all of the cylinders of the engine. The ECM may activate one ormore deactivated cylinders, for example, when the torque requestincreases.

Airflow into the engine may vary when one or more cylinders areactivated or deactivated. The ECM of the present disclosure determines atarget mass air flowrate (MAF) through a throttle valve for use when oneor more cylinders are activated or deactivated. The ECM controls openingof a throttle valve of the engine based on the target MAF. Controllingthe throttle valve based on the target MAF may provide smoother air percylinder (APC) conditions and, therefore smoother engine torque output,while the cylinder(s) are activated or deactivated.

Referring now to FIG. 1, a functional block diagram of an example enginesystem 100 is presented. The engine system 100 includes an engine 102that combusts an air/fuel mixture to produce drive torque for a vehiclebased on driver input from a driver input module 104. Air is drawn intoan intake manifold 110 through a throttle valve 112. For example only,the throttle valve 112 may include a butterfly valve having a rotatableblade. An engine control module (ECM) 114 controls a throttle actuatormodule 116, which regulates opening of the throttle valve 112 to controlthe amount of air drawn into the intake manifold 110.

Air from the intake manifold 110 is drawn into cylinders of the engine102. While the engine 102 may include multiple cylinders, forillustration purposes a single representative cylinder 118 is shown. Forexample only, the engine 102 may include 2, 3, 4, 5, 6, 8, 10, and/or 12cylinders. The ECM 114 may instruct a cylinder actuator module 120 toselectively deactivate some of the cylinders, which may improve fueleconomy under certain engine operating conditions.

The engine 102 may operate using a four-stroke cycle. The four strokes,described below, may be referred to as the intake stroke, thecompression stroke, the combustion stroke, and the exhaust stroke.During each revolution of a crankshaft (not shown), two of the fourstrokes occur within the cylinder 118. Therefore, two crankshaftrevolutions are necessary for the cylinder 118 to experience all four ofthe strokes.

During the intake stroke, air from the intake manifold 110 is drawn intothe cylinder 118 through an intake valve 122. The ECM 114 controls afuel actuator module 124, which regulates fuel injection to achieve atarget air/fuel ratio. Fuel may be injected into the intake manifold 110at a central location or at multiple locations, such as near the intakevalve 122 of each of the cylinders. In various implementations (notshown), fuel may be injected directly into the cylinders or into mixingchambers associated with the cylinders. The fuel actuator module 124 mayhalt injection of fuel to cylinders that are deactivated.

The injected fuel mixes with air and creates an air/fuel mixture in thecylinder 118. During the compression stroke, a piston (not shown) withinthe cylinder 118 compresses the air/fuel mixture. While not shown, theengine 102 may be a compression-ignition engine, in which casecompression within the cylinder 118 ignites the air/fuel mixture.Alternatively, as shown, the engine 102 may be a spark-ignition engine,in which case a spark actuator module 126 energizes a spark plug 128 inthe cylinder 118 based on a signal from the ECM 114, which ignites theair/fuel mixture. The timing of the spark may be specified relative tothe time when the piston is at its topmost position, referred to as topdead center (TDC).

The spark actuator module 126 may be controlled by a timing signalspecifying how far before or after TDC to generate the spark. Becausepiston position is directly related to crankshaft rotation, operation ofthe spark actuator module 126 may be synchronized with crankshaft angle.The spark actuator module 126 may halt provision of spark to deactivatedcylinders. Generating spark may be referred to as a firing event. Thespark actuator module 126 may have the ability to vary the timing of thespark for each firing event. The spark actuator module 126 may vary thespark timing for a next firing event when the spark timing is changedbetween a last firing event and the next firing event.

During the combustion stroke, the combustion of the air/fuel mixturedrives the piston away from TDC, thereby driving the crankshaft. Thecombustion stroke may be defined as the time between the piston reachingTDC and the time at which the piston reaches bottom dead center (BDC).During the exhaust stroke, the piston begins moving away from BDC andexpels the byproducts of combustion through an exhaust valve 130. Thebyproducts of combustion are exhausted from the vehicle via an exhaustsystem 134.

The intake valve 122 may be controlled by an intake camshaft 140, whilethe exhaust valve 130 may be controlled by an exhaust camshaft 142. Invarious implementations, multiple intake camshafts (including the intakecamshaft 140) may control multiple intake valves (including the intakevalve 122) for the cylinder 118 and/or may control the intake valves(including the intake valve 122) of multiple banks of cylinders(including the cylinder 118). Similarly, multiple exhaust camshafts(including the exhaust camshaft 142) may control multiple exhaust valvesfor the cylinder 118 and/or may control exhaust valves (including theexhaust valve 130) for multiple banks of cylinders (including thecylinder 118). The cylinder actuator module 120 may deactivate thecylinder 118 by disabling opening of the intake valve 122 and/or theexhaust valve 130. In various other implementations, the intake valve122 and/or the exhaust valve 130 may be controlled by devices other thancamshafts, such as camless valve actuators.

The time when the intake valve 122 is opened may be varied with respectto piston TDC by an intake cam phaser 148. The time when the exhaustvalve 130 is opened may be varied with respect to piston TDC by anexhaust cam phaser 150. A phaser actuator module 158 may control theintake cam phaser 148 and the exhaust cam phaser 150 based on signalsfrom the ECM 114. When implemented, variable valve lift (not shown) mayalso be controlled by the phaser actuator module 158.

The engine system 100 may include a boost device that providespressurized air to the intake manifold 110. For example, FIG. 1 shows aturbocharger including a hot turbine 160-1 that is powered by hotexhaust gases flowing through the exhaust system 134. The turbochargeralso includes a cold air compressor 160-2 that is driven by the turbine160-1. The compressor 160-2 compresses air leading into the throttlevalve 112. In various implementations, a supercharger (not shown),driven by the crankshaft, may compress air from the throttle valve 112and deliver the compressed air to the intake manifold 110.

A wastegate 162 may allow exhaust to bypass the turbine 160-1, therebyreducing the boost (the amount of intake air compression) provided bythe turbocharger. The ECM 114 may control the turbocharger via a boostactuator module 164. The boost actuator module 164 may modulate theboost of the turbocharger by controlling opening of the wastegate 162.In various implementations, multiple turbochargers may be controlled bythe boost actuator module 164. The turbocharger may have variablegeometry, which may be controlled by the boost actuator module 164.

An intercooler (not shown) may dissipate some of the heat contained inthe compressed air charge, which is generated as the air is compressed.The compressed air charge may also have absorbed heat from components ofthe exhaust system 134. Although shown separated for purposes ofillustration, the turbine 160-1 and the compressor 160-2 may be attachedto each other, placing intake air in close proximity to hot exhaust.

The engine system 100 may include an exhaust gas recirculation (EGR)valve 170, which selectively redirects exhaust gas back to the intakemanifold 110. The EGR valve 170 may be located upstream of theturbocharger's turbine 160-1. The EGR valve 170 may be controlled by anEGR actuator module 172.

The engine system 100 may measure the rotational speed of the crankshaftin revolutions per minute (RPM) using an RPM sensor 180. The speed ofthe crankshaft may be referred to as an engine speed. The temperature ofthe engine coolant may be measured using an engine coolant temperature(ECT) sensor 182. The ECT sensor 182 may be located within the engine102 or at other locations where the coolant is circulated, such as aradiator (not shown).

The pressure within the intake manifold 110 may be measured using amanifold absolute pressure (MAP) sensor 184. In various implementations,engine vacuum, which is the difference between ambient air pressure andthe pressure within the intake manifold 110, may be measured. The massflow rate of air flowing into the intake manifold 110 may be measuredusing a mass air flow (MAF) sensor 186. In various implementations, theMAF sensor 186 may be located in a housing that also includes thethrottle valve 112.

The throttle actuator module 116 may monitor the position of thethrottle valve 112 using one or more throttle position sensors (TPS)190. The ambient temperature of air being drawn into the engine 102 maybe measured using an intake air temperature (IAT) sensor 192. The enginesystem 100 may also include one or more other sensors. The ECM 114 mayuse signals from the sensors to make control decisions for the enginesystem 100.

The ECM 114 may communicate with a transmission control module 194 tocoordinate shifting gears in a transmission (not shown). For example,the ECM 114 may reduce engine torque during a gear shift. The ECM 114may communicate with a hybrid control module 196 to coordinate operationof the engine 102 and an electric motor 198.

The electric motor 198 may also function as a generator, and may be usedto produce electrical energy for use by vehicle electrical systemsand/or for storage in a battery. In various implementations, variousfunctions of the ECM 114, the transmission control module 194, and thehybrid control module 196 may be integrated into one or more modules.

Each system that varies an engine parameter may be referred to as anactuator. Each system receives a target actuator value. For example, thethrottle actuator module 116 may be referred to as an actuator, and atarget throttle opening (e.g., area) may be referred to as the targetactuator value. In the example of FIG. 1, the throttle actuator module116 achieves the target throttle opening by adjusting an angle of theblade of the throttle valve 112.

Similarly, the spark actuator module 126 may be referred to as anactuator, while the corresponding target actuator value may be a targetspark timing relative to piston TDC. Other actuators may include thecylinder actuator module 120, the fuel actuator module 124, the phaseractuator module 158, the boost actuator module 164, and the EGR actuatormodule 172. For these actuators, the target actuator values may includetarget number of activated cylinders, target fueling parameters, targetintake and exhaust cam phaser angles, target wastegate duty cycle, andtarget EGR valve opening area, respectively. The ECM 114 may generatethe target actuator values to cause the engine 102 to generate a targetengine output torque.

Referring now to FIG. 2, a functional block diagram of an example enginecontrol system is presented. An example implementation of the ECM 114includes a driver torque module 202, an axle torque arbitration module204, and a propulsion torque arbitration module 206. The ECM 114 mayinclude a hybrid optimization module 208. The ECM 114 also includes areserves/loads module 220, a torque requesting module 224, an aircontrol module 228, a spark control module 232, a cylinder controlmodule 236, and a fuel control module 240. The ECM 114 also includes anair per cylinder (APC) torque estimation module 244, a MAP torqueestimation module 246, a boost control module 248, a phaser controlmodule 252, and an EGR control module 253.

The driver torque module 202 may determine a driver torque request 254based on a driver input 255 from the driver input module 104. The driverinput 255 may be based on, for example, a position of an acceleratorpedal and a position of a brake pedal. The driver input 255 may also bebased on cruise control, which may be an adaptive cruise control systemthat varies vehicle speed to maintain a predetermined followingdistance. The driver torque module 202 may store one or more mappings ofaccelerator pedal position to target torque and may determine the drivertorque request 254 based on a selected one of the mappings.

An axle torque arbitration module 204 arbitrates between the drivertorque request 254 and other axle torque requests 256. Axle torque(torque at the wheels) may be produced by various sources including anengine and/or an electric motor. For example, the axle torque requests256 may include a torque reduction requested by a traction controlsystem when positive wheel slip is detected. Positive wheel slip occurswhen axle torque overcomes friction between the wheels and the roadsurface, and the wheels begin to slip against the road surface. The axletorque requests 256 may also include a torque increase request tocounteract negative wheel slip, where a tire of the vehicle slips in theother direction with respect to the road surface because the axle torqueis negative.

The axle torque requests 256 may also include brake management requestsand vehicle over-speed torque requests. Brake management requests mayreduce axle torque to ensure that the axle torque does not exceed theability of the brakes to hold the vehicle when the vehicle is stopped.Vehicle over-speed torque requests may reduce the axle torque to preventthe vehicle from exceeding a predetermined speed. The axle torquerequests 256 may also be generated by vehicle stability control systems.

The axle torque arbitration module 204 outputs a predicted torquerequest 257 and an immediate torque request 258 based on the results ofarbitrating between the received torque requests 254 and 256. Asdescribed below, the predicted and immediate torque requests 257 and 258from the axle torque arbitration module 204 may selectively be adjustedby other modules of the ECM 114 before being used to control theactuators of the engine system 100.

In general terms, the immediate torque request 258 is the amount ofcurrently target axle torque, while the predicted torque request 257 isthe amount of axle torque that may be needed on short notice. The ECM114 controls the engine system 100 to produce an axle torque equal tothe immediate torque request 258. However, different combinations ofactuator values may result in the same axle torque. The ECM 114 maytherefore adjust the target actuator values to enable a fastertransition to the predicted torque request 257, while still maintainingthe axle torque at the immediate torque request 258.

In various implementations, the predicted torque request 257 may be setbased on the driver torque request 254. The immediate torque request 258may be set to less than the predicted torque request 257 under somecircumstances, such as when the driver torque request 254 is causingwheel slip on an icy surface. In such a case, a traction control system(not shown) may request a reduction via the immediate torque request258, and the ECM 114 reduces the engine torque output to the immediatetorque request 258. However, the ECM 114 performs the reduction so theengine system 100 can quickly resume producing the predicted torquerequest 257 once the wheel slip stops.

In general terms, the difference between the immediate torque request258 and the (generally higher) predicted torque request 257 can bereferred to as a torque reserve. The torque reserve may represent theamount of additional torque (above the immediate torque request 258)that the engine system 100 can begin to produce with minimal delay. Fastengine actuators are used to increase or decrease current axle torquewith minimal delay. As described in more detail below, fast engineactuators are defined in contrast with slow engine actuators.

In various implementations, fast engine actuators are capable of varyingaxle torque within a range, where the range is established by the slowengine actuators. The upper limit of the range is the predicted torquerequest 257, while the lower limit of the range is limited by the torque(varying) capacity of the fast actuators. For example only, fastactuators may only be able to reduce axle torque by a first amount,where the first amount is a measure of the torque capacity of the fastactuators. The first amount may vary based on engine operatingconditions set by the slow engine actuators.

When the immediate torque request 258 is within the range, fast engineactuators can be controlled to cause the axle torque to be equal to theimmediate torque request 258. When the ECM 114 requests the predictedtorque request 257 to be output, the fast engine actuators can becontrolled to vary the axle torque to the top of the range, which is thepredicted torque request 257.

In general terms, fast engine actuators can change the axle torque morequickly than slow engine actuators. Slow actuators may respond moreslowly to changes in their respective actuator values than fastactuators do. For example, a slow actuator may include mechanicalcomponents that require time to move from one position to another inresponse to a change in actuator value. A slow actuator may also becharacterized by the amount of time it takes for the axle torque tobegin to change once the slow actuator begins to implement the changedactuator value. Generally, this amount of time will be longer for slowactuators than for fast actuators. In addition, even after beginning tochange, the axle torque may take longer to fully respond to a change ina slow actuator.

For example only, the ECM 114 may set actuator values for slow actuatorsto values that would enable the engine system 100 to produce thepredicted torque request 257 if the fast actuators were set toappropriate values. Meanwhile, the ECM 114 may set target actuatorvalues for fast actuators to values that, given the slow actuatorvalues, cause the engine system 100 to produce the immediate torquerequest 258 instead of the predicted torque request 257.

The fast actuators therefore cause the engine system 100 to produce theimmediate torque request 258. When the ECM 114 decides to transition theaxle torque from the immediate torque request 258 to the predictedtorque request 257, the ECM 114 changes the target actuator values forone or more fast actuators to values that correspond to the predictedtorque request 257. Because the target actuator values for the slowactuators have already been set based on the predicted torque request257, the engine system 100 is able to produce the predicted torquerequest 257 after only the (minimal) delay imposed by the fastactuators. In other words, the longer delay that would otherwise resultfrom changing axle torque using slow actuators is avoided.

For example only, in a spark-ignition engine, spark timing may be a fastactuator value, while throttle opening may be a slow actuator value.Spark-ignition engines may combust fuels including, for example,gasoline and ethanol, by applying a spark. By contrast, in acompression-ignition engine, fuel flow may be a fast actuator value,while throttle opening may be used as an actuator value for enginecharacteristics other than torque. Compression-ignition engines maycombust fuels including, for example, diesel fuel, via compression.

When the engine 102 is a spark-ignition engine, the spark actuatormodule 126 may be a fast actuator and the throttle actuator module 116may be a slow actuator. After receiving a new target actuator value, thespark actuator module 126 may be able to change spark timing for thefollowing firing event. When the spark timing (also called sparkadvance) for a firing event is set to an optimum value, a maximum amountof torque may be produced in the combustion stroke immediately followingthe firing event. However, a spark timing deviating from the optimumvalue may reduce the amount of torque produced in the combustion stroke.Therefore, the spark actuator module 126 may be able to vary engineoutput torque as soon as the next firing event occurs by varying sparktiming. For example only, a table of optimum spark timings correspondingto different engine operating conditions may be determined during acalibration phase of vehicle design, and the optimum value is selectedfrom the table based on current engine operating conditions.

By contrast, changes in throttle opening take longer to affect engineoutput torque. The throttle actuator module 116 changes the throttleopening by adjusting the angle of the blade of the throttle valve 112.Therefore, once a new actuator value is received, there is a mechanicaldelay as the throttle valve 112 moves from its previous position to anew position based on the new target actuator value. In addition, airflow changes based on the throttle opening are subject to air transportdelays in the intake manifold 110. Further, increased air flow in theintake manifold 110 is not realized as an increase in engine outputtorque until the cylinder 118 receives additional air in the next intakestroke, compresses the additional air, and commences the combustionstroke.

Using these actuators as an example, a torque reserve can be created bysetting the throttle opening to a value that would allow the engine 102to produce the predicted torque request 257. Meanwhile, the spark timingcan be set based on the immediate torque request 258, which is less thanthe predicted torque request 257. Although the throttle openinggenerates enough air flow for the engine 102 to produce the predictedtorque request 257, the spark timing is retarded (which reduces torque)based on the immediate torque request 258. The engine output torque willtherefore be equal to the immediate torque request 258.

When additional torque is needed, the spark timing can be set based onthe predicted torque request 257 or a torque between the predicted andimmediate torque requests 257 and 258. By the following firing event,the spark actuator module 126 may return the spark timing to an optimumvalue, which allows the engine 102 to produce the full engine outputtorque achievable with the air flow already present. The engine outputtorque may therefore be quickly increased to the predicted torquerequest 257 without experiencing delays from changing the throttleopening.

The axle torque arbitration module 204 may output the predicted torquerequest 257 and the immediate torque request 258 to a propulsion torquearbitration module 206. In various implementations, the axle torquearbitration module 204 may output the predicted and immediate torquerequests 257 and 258 to the hybrid optimization module 208.

The hybrid optimization module 208 may determine how much torque shouldbe produced by the engine 102 and how much torque should be produced bythe electric motor 198. The hybrid optimization module 208 then outputsmodified predicted and immediate torque requests 259 and 260,respectively, to the propulsion torque arbitration module 206. Invarious implementations, the hybrid optimization module 208 may beimplemented in the hybrid control module 196.

The predicted and immediate torque requests received by the propulsiontorque arbitration module 206 are converted from an axle torque domain(torque at the wheels) into a propulsion torque domain (torque at thecrankshaft). This conversion may occur before, after, as part of, or inplace of the hybrid optimization module 208.

The propulsion torque arbitration module 206 arbitrates betweenpropulsion torque requests 290, including the converted predicted andimmediate torque requests. The propulsion torque arbitration module 206generates an arbitrated predicted torque request 261 and an arbitratedimmediate torque request 262. The arbitrated torque requests 261 and 262may be generated by selecting a winning request from among receivedtorque requests. Alternatively or additionally, the arbitrated torquerequests may be generated by modifying one of the received requestsbased on another one or more of the received torque requests.

For example, the propulsion torque requests 290 may include torquereductions for engine over-speed protection, torque increases for stallprevention, and torque reductions requested by the transmission controlmodule 194 to accommodate gear shifts. The propulsion torque requests290 may also result from clutch fuel cutoff, which reduces the engineoutput torque when the driver depresses the clutch pedal in a manualtransmission vehicle to prevent a flare (rapid rise) in engine speed.

The propulsion torque requests 290 may also include an engine shutoffrequest, which may be initiated when a critical fault is detected. Forexample only, critical faults may include detection of vehicle theft, astuck starter motor, electronic throttle control problems, andunexpected torque increases. In various implementations, when an engineshutoff request is present, arbitration selects the engine shutoffrequest as the winning request. When the engine shutoff request ispresent, the propulsion torque arbitration module 206 may output zero asthe arbitrated predicted and immediate torque requests 261 and 262.

In various implementations, an engine shutoff request may simply shutdown the engine 102 separately from the arbitration process. Thepropulsion torque arbitration module 206 may still receive the engineshutoff request so that, for example, appropriate data can be fed backto other torque requestors. For example, all other torque requestors maybe informed that they have lost arbitration.

The reserves/loads module 220 receives the arbitrated predicted andimmediate torque requests 261 and 262. The reserves/loads module 220 mayadjust the arbitrated predicted and immediate torque requests 261 and262 to create a torque reserve and/or to compensate for one or moreloads. The reserves/loads module 220 then outputs adjusted predicted andimmediate torque requests 263 and 264 to the torque requesting module224.

For example only, a catalyst light-off process or a cold start emissionsreduction process may require retarded spark timing. The reserves/loadsmodule 220 may therefore increase the adjusted predicted torque request263 above the adjusted immediate torque request 264 to create retardedspark for the cold start emissions reduction process. In anotherexample, the air/fuel ratio of the engine and/or the mass air flow maybe directly varied, such as by diagnostic intrusive equivalence ratiotesting and/or new engine purging. Before beginning these processes, atorque reserve may be created or increased to quickly offset decreasesin engine output torque that result from leaning the air/fuel mixtureduring these processes.

The reserves/loads module 220 may also create or increase a torquereserve in anticipation of a future load, such as power steering pumpoperation or engagement of an air conditioning (A/C) compressor clutch.The reserve for engagement of the A/C compressor clutch may be createdwhen the driver first requests air conditioning. The reserves/loadsmodule 220 may increase the adjusted predicted torque request 263 whileleaving the adjusted immediate torque request 264 unchanged to producethe torque reserve. Then, when the A/C compressor clutch engages, thereserves/loads module 220 may increase the adjusted immediate torquerequest 264 by the estimated load of the A/C compressor clutch.

The torque requesting module 224 receives the adjusted predicted andimmediate torque requests 263 and 264. The torque requesting module 224determines how the adjusted predicted and immediate torque requests 263and 264 will be achieved. The torque requesting module 224 may be enginetype specific. For example, the torque requesting module 224 may beimplemented differently or use different control schemes forspark-ignition engines versus compression-ignition engines.

In various implementations, the torque requesting module 224 may definea boundary between modules that are common across all engine types andmodules that are engine type specific. For example, engine types mayinclude spark-ignition and compression-ignition. Modules prior to thetorque requesting module 224, such as the propulsion torque arbitrationmodule 206, may be common across engine types, while the torquerequesting module 224 and subsequent modules may be engine typespecific.

For example, in a spark-ignition engine, the torque requesting module224 may vary the opening of the throttle valve 112 as a slow actuatorthat allows for a wide range of torque control. The torque requestingmodule 224 may disable cylinders using the cylinder actuator module 120,which also provides for a wide range of torque control, but may also beslow and may involve drivability and emissions concerns. The torquerequesting module 224 may use spark timing as a fast actuator. However,spark timing may not provide as much range of torque control. Inaddition, the amount of torque control possible with changes in sparktiming (referred to as spark reserve capacity) may vary as air flowchanges.

In various implementations, the torque requesting module 224 maygenerate an air torque request 265 based on the adjusted predictedtorque request 263. The air torque request 265 may be equal to theadjusted predicted torque request 263, setting air flow so that theadjusted predicted torque request 263 can be achieved by changes toother (e.g., fast) actuators.

Target actuator values for airflow controlling actuators may bedetermined based on the air torque request 265. For example only, theair control module 228 (see also FIG. 3) may determine a target manifoldabsolute pressure (MAP) 266, a target throttle opening (e.g., area) 267,a second target air per cylinder (APC2) 268, and a third target APC(APC3) 291 based on the air torque request 265. Determination of thesecond and third target APCs 268 and 291 are discussed further below.

The boost control module 248 may determine a target duty cycle 269 forthe wastegate 162 based on the target MAP 266. While the target dutycycle 269 will be discussed, the boost control module 248 may determineanother suitable value for controlling the wastegate 162. The phasercontrol module 252 may determine target intake and exhaust cam phaserangles 270 and 271 based on the second target APC 268. The EGR controlmodule 253 determines a target EGR opening 292 based on the third targetAPC 291.

The torque requesting module 224 may also generate a spark torquerequest 272, a cylinder shut-off torque request 273, and a fuel torquerequest 274. The spark control module 232 may determine how much toretard the spark timing (which reduces engine output torque) from anoptimum spark timing based on the spark torque request 272. For exampleonly, a torque relationship may be inverted to solve for a desired sparktiming 299. For a given torque request (T_(des)), the desired sparktiming (S_(des)) 299 may be determined based on:

S _(des) =f ⁻¹(T _(des),APC,I,E,AF,OT,#).  (0)

This relationship may be embodied as an equation and/or as a lookuptable. The air/fuel ratio (AF) may be the actual air/fuel ratio, asreported by the fuel control module 240. APC is an APC of the engine102, I is an intake cam phaser angle, E is an exhaust cam phaser angle,OT is an oil temperature, and # is a number of activated cylinders. Thespark control module 232 may also generate a target spark timing 275, asdiscussed further below in conjunction with FIG. 3.

When the spark timing is set to the optimum spark timing, the resultingtorque may be as close to a minimum spark advance for best torque (MBTspark timing) as possible. Best torque refers to the maximum engineoutput torque that is generated for a given air flow as spark timing isadvanced, while using fuel having an octane rating greater than apredetermined octane rating and using stoichiometric fueling. The sparktiming at which this best torque occurs is referred to as an MBT sparktiming. The optimum spark timing may differ slightly from MBT sparktiming because of, for example, fuel quality (such as when lower octanefuel is used) and environmental factors. The engine output torque at theoptimum spark timing may therefore be less than MBT.

The cylinder shut-off torque request 273 may be used by the cylindercontrol module 236 to determine a target number of cylinders todeactivate 276. The cylinder control module 236 may also instruct thefuel control module 240 to stop providing fuel for deactivated cylindersand may instruct the spark control module 232 to stop providing sparkfor deactivated cylinders. The spark control module 232 may stopproviding spark to a cylinder once an fuel/air mixture that is alreadypresent in the cylinder has been combusted.

The fuel control module 240 may vary the amount of fuel provided to eachcylinder based on the fuel torque request 274. More specifically, thefuel control module 240 may generate target fueling parameters 277 basedon the fuel torque request 274. The target fueling parameters 277 mayinclude, for example, target mass of fuel, target injection startingtiming, and target number of fuel injections.

The air control module 228 generates the target MAP 266 based on a MAPestimated torque 278. The MAP estimated torque 278 corresponds to anestimated value of the present engine torque output determined based ona MAP 279 measured using the MAP sensor 184. The MAP torque estimationmodule 246 generates the MAP estimated torque 278 based on the MAP 279and other measured engine operating parameters. For example, the MAPtorque estimation module 246 generates the MAP estimated torque 278using the relationship:

T _(MAP) =f(MAP,RPM,S _(M) ,I _(M) ,E _(M),AF,OT,#),  (1)

where T_(MAP) is the MAP estimated torque 278, MAP is the MAP 279, RPMis engine speed (rotational speed of the crankshaft), S_(M) is presentspark timing 280 being used by the spark actuator module 126, I_(M) is ameasured intake cam phaser angle 281, E_(M) is a measured exhaust camphaser angle 282, AF is the present air/fuel ratio being used by thefuel actuator module 124, OT is oil temperature, and # is the presentnumber of cylinders that are activated. The relationship may be embodiedas an equation or as a look-up table.

The phaser control module 252 may provide the measured intake andexhaust cam phaser angles 281 and 282. The phaser control module 252 maygenerate the measured intake and exhaust cam phaser angles 281 and 282based on previous values of the measured intake and exhaust cam phaserangles 281 and 282 and the target intake and exhaust cam phaser angles270 and 271. For example, the phaser control module 252 may generate themeasured intake and exhaust cam phaser angles 281 and 282 using therelationships:

I _(M) =f(I _(T))+k*(I _(T) −I _(M) _(—) _(PREV)), and  (2)

E _(M) =f(E _(T))+k*(E _(T) −E _(M) _(—) _(PREV)),  (3)

where I_(M) is the measured intake cam phaser angle 281, I_(T) is thetarget intake cam phaser angle 270, k is a predetermined scalar/gainvalue, I_(M) _(—) _(PREV) is a previous value of the measured intake camphaser angle 281, E_(M) is the measured exhaust cam phaser angle 282,E_(T) is the target exhaust cam phaser angle 271, k is a predeterminedscalar/gain value, and E_(M) _(—) _(PREV) is a previous value of themeasured exhaust cam phaser angle 282.

The air control module 228 generates various target values further basedon a first APC estimated torque 283. The first APC estimated torque 283corresponds to an estimated value of the present engine torque outputdetermined based on a present APC 284. The present APC 284 is determinedbased on one or more measured parameters, such as the MAF, the MAP,and/or the IAT.

The APC torque estimation module 244 generates the first APC estimatedtorque 283 based on the present APC 284 and other measured engineoperating parameters. For example, the APC torque estimation module 244may generate the first APC estimated torque 283 using the relationship:

T _(APC1) =f(APC_(P),RPM,S _(M) ,I _(M) ,E _(M),AF,OT,#),  (4)

where T_(APC1) is the first APC estimated torque 283, APC_(P) is thepresent APC 284, RPM is the engine speed, S_(M) is the present sparktiming 280 being used by the spark actuator module 126, I_(M) is themeasured intake cam phaser angle 281, E_(M) is the measured exhaust camphaser angle 282, AF is the present air/fuel ratio being used by thefuel actuator module 124, OT is the oil temperature, and # is thepresent number of cylinders that are activated. The relationship may beembodied as an equation or as a look-up table.

The APC torque estimation module 244 also generates a second APCestimated torque 298 based on the present APC 284 and the target intakeand exhaust cam phaser angles 270 and 271. For example, the APC torqueestimation module 244 may generate the second APC estimated torque 298using the relationship:

T _(APC2) =f(APC_(M),RPM,S _(M) ,I _(T) ,E _(T),AF,OT,#),  (5)

where T_(APC2) is the second APC estimated torque 298, APC_(M) is thepresent APC 284, RPM is the engine speed, S_(M) is the present sparktiming 280 being used by the spark actuator module 126, I_(T) is thetarget intake cam phaser angle 270, E_(T) is the target exhaust camphaser angle 271, AF is the present air/fuel ratio being used by thefuel actuator module 124, OT is the oil temperature, and # is thepresent number of cylinders that are activated. The relationship may beembodied as an equation or as a look-up table.

The air control module 228 may output the target throttle opening 267 tothe throttle actuator module 116. The throttle actuator module 116regulates the throttle valve 112 to produce the target throttle opening267. The air control module 228 outputs the target MAP 266 to the boostcontrol module 248. The boost control module 248 controls the wastegate162 based on the target MAP 266. The air control module 228 outputs thesecond target APC 268 to the phaser control module 252. Based on thesecond target APC 268 and the engine speed (and/or crankshaft position),the phaser control module 252 may control positions of the intake and/orexhaust cam phasers 148 and 150.

Referring now to FIG. 3, a functional block diagram of an exampleimplementation of the air control module 228 is presented. A delay andrate limit module 302 applies one or more shaping actions to the airtorque request 265 to produce a shaped air torque request 303. Morespecifically, the delay and rate limit module 302 stores the air torquerequest 265 for a delay period before outputting the stored air torquerequest as a delayed air torque request (not shown). The delay and ratelimit module 302 may determine the delay period based on an EGR value(e.g., opening or mass flow rate) and/or the engine speed (RPM).

The delay and rate limit module 302 applies a rate limit to the delayedair torque request to produce the shaped air torque request 303. Inother words, the delay and rate limit module 302 adjusts the shaped airtorque request 303 toward the delayed air torque request by up to amaximum amount per predetermined period. The delay and rate limit module302 may determine the maximum amount based on the EGR value and/or theengine speed. While delaying and rate limiting shaping actions have beendescribed, one or more other shaping actions may also be performed.

A torque error module 304 determines a torque error 308 based on adifference between the shaped air torque request 303 and the first APCestimated torque 283. For example, the torque error module 304 may setthe torque error 308 equal to the air torque request 265 minus the firstAPC estimated torque 283.

An adjustment module 312 generates a torque adjustment 316 based on thetorque error 308. The adjustment module 312 may generate the torqueadjustment 316, for example, using the relationship:

T _(ADJ) =K _(P)*(T _(ERROR))+K _(I) *∫T _(ERROR) ¶t,  (6)

where T_(ADJ) is the torque adjustment 316, K_(P) is a proportionalgain, T_(ERROR) is the torque error 308, and K_(I) is an integral gain.K_(P)*(T_(ERROR)) will be referred to as a proportional (P) torqueadjustment, and K_(I)*∫T_(ERROR)∂t is referred to as an integral (I)torque adjustment 318. The torque adjustment 316 is equal to the sum ofthe P torque adjustment and the I torque adjustment 318. In variousimplementations, another suitable type of closed-loop controller may beused to generate the torque adjustment 316 based on the torque error308.

A target determination module 320 determines a target torque 324 basedon the shaped air torque request 303 and the torque adjustment 316. Forexample, the target determination module 320 may set the target torque324 equal to the shaped air torque request 303 plus the torqueadjustment 316.

A target APC module 328 generates a first target APC (APC1) 329. FIG. 4is a functional block diagram of an example implementation of the targetAPC module 328. Referring now to FIGS. 3 and 4, a first APCdetermination module 404 determines the first target APC 329 based onthe target torque 324, the target spark timing 275, and selected intakeand exhaust cam phaser angles 330 and 331. The first APC determinationmodule 404 determines the first target APC 329 further based on theengine speed, the present air/fuel ratio, the oil temperature, and thepresent number of active cylinders. Relationship (4) provided above maybe inverted and solved to determine the first target APC 329. Forexample, the first APC determination module 404 may generate the firsttarget APC 329 using the relationship:

APC_(T) _(—) ₁ =T ⁻¹(T _(T),RPM,S _(T) ,I _(SEL) ,E_(SEL),AF,OT,#),  (7)

where APC_(T) _(—) ₁ is the first target APC 329, T_(T) is the targettorque 324, RPM is engine speed, S_(T) is the target spark timing 275,I_(SEL) is the selected intake cam phaser angle 330, E_(SEL) is theselected exhaust cam phaser angle 331, AF is the present air/fuel ratiobeing used by the fuel actuator module 124, OT is the oil temperature, #is the present number of cylinders that are activated, and T⁻¹ denotesinversion of relationship (4) above used to relate the present APC 284to the first APC estimated torque 283. In various implementations, thetarget intake and exhaust cam phaser angles 270 and 271 may be used inplace of the selected intake and exhaust cam phaser angles 330 and 331.This relationship may be embodied as an equation or as a look-up table.Generation of the selected intake and exhaust cam phaser angles 330 and331 is discussed further below.

The target APC module 328 also generates the second and third targetAPCs 268 and 291. A second APC determination module 408 determines thesecond target APC 268 based on a phaser target torque 412, the targetspark timing 275, and selected intake and exhaust cam phaser angles 330and 331. The second APC determination module 408 determines the secondtarget APC 268 further based on the engine speed, the present air/fuelratio, the oil temperature, and the present number of active cylinders.Relationship (4) provided above may be inverted and solved to determinethe second target APC 268. For example, the second APC determinationmodule 408 may generate the second target APC 268 using therelationship:

APC_(T) _(—) ₂ =T ⁻¹(T _(PTT),RPM,S _(T) ,I _(SEL) ,E_(SEL),AF,OT,#),  (8)

where APC_(T) _(—) ₂ is the second target APC 268, T_(PTT) is the phasertarget torque 412, RPM is engine speed, S_(T) is the target spark timing275, I_(SEL) is the selected intake cam phaser angle 330, E_(SEL) is theselected exhaust cam phaser angle 331, AF is the present air/fuel ratiobeing used by the fuel actuator module 124, OT is the oil temperature, #is the present number of cylinders that are activated, and T⁻¹ denotesinversion of relationship (4) above used to relate the present APC 284to the first APC estimated torque 283. In various implementations, thetarget intake and exhaust cam phaser angles 270 and 271 may be used inplace of the selected intake and exhaust cam phaser angles 330 and 331.This relationship may be embodied as an equation or as a look-up table.

A target phaser torque module 416 determines the phaser target torque412 based on the shaped air torque request 303 and a phaser torqueadjustment 420. For example, the target phaser torque module 416 may setthe phaser target torque 412 equal to the phaser torque adjustment 420plus the shaped air torque request 303.

A first selection module 424 sets the phaser torque adjustment 420 toone of zero and the I torque adjustment 318 based on a first selectionsignal 428. For example, the first selection module 424 may set thephaser torque adjustment 420 to zero when the first selection signal 428is in a first state and set the phaser torque adjustment 420 to the Itorque adjustment 318 when the first selection signal 428 is in a secondstate. The state of the first selection signal 428 may be set, forexample, during the calibration stage of vehicle design. For example,the first selection signal 428 may be set to the first state when thephaser control module 252 can change the target intake and/or exhaustphaser angles 270 and 271 at greater than a predetermined rate. Thefirst selection signal 428 may be set to the second state when thephaser control module 252 is limited to changing the target intakeand/or exhaust phaser angles 270 and 271 at less than the predeterminedrate.

As stated above, the phaser control module 252 (FIG. 2) generates thetarget intake and exhaust cam phaser angles 270 and 271 based on thesecond target APC 268. More specifically, the phaser control module 252may determine the target intake and exhaust cam phaser angles 270 and271 based on the second target APC 268 and the engine speed. Forexample, the phaser control module 252 may generate the target intakeand exhaust cam phaser angles 270 and 271 using the relationships:

I _(T) =f(RPM,APC_(T) _(—) ₂); and  (9)

E _(T) =f(RPM,APC_(T) _(—) ₂),  (10)

where I_(T) is the target intake cam phaser angle 270, RPM is the enginespeed, APC_(T) _(—) ₂ is the second target APC 268, and E_(T) is thetarget exhaust cam phaser angle 271. These relationships may be embodiedas equations or as look-up tables. The phaser actuator module 158controls the intake and exhaust cam phasers 148 and 150 based on thetarget intake and exhaust cam phaser angles 270 and 271, respectively.

A third APC determination module 432 determines the third target APC 291based on an EGR target torque 436, the target spark timing 275, andselected intake and exhaust cam phaser angles 330 and 331. The third APCdetermination module 432 determines the third target APC 291 furtherbased on the engine speed, the present air/fuel ratio, the oiltemperature, and the present number of active cylinders. Relationship(4) provided above may be inverted and solved to determine the thirdtarget APC 291. For example, the third APC determination module 432 maygenerate the third target APC 291 using the relationship:

APC_(T) _(—) ₃ =T ⁻¹(T _(EGRT),RPM,S _(T) ,I _(SEL) ,E_(SEL),AF,OT,#),  (11)

where APC_(T) _(—) ₃ is the third target APC 291, T_(EGRT) is the EGRtarget torque 436, RPM is engine speed, S_(T) is the target spark timing275, I_(SEL) is the selected intake cam phaser angle 330, E_(SEL) is theselected exhaust cam phaser angle 331, AF is the present air/fuel ratiobeing used by the fuel actuator module 124, OT is the oil temperature, #is the present number of cylinders that are activated, and T⁻¹ denotesinversion of relationship (4) above used to relate the present APC 284to the first APC estimated torque 283. In various implementations, thetarget intake and exhaust cam phaser angles 270 and 271 may be used inplace of the selected intake and exhaust cam phaser angles 330 and 331.This relationship may be embodied as an equation or as a look-up table.

A target EGR torque module 440 determines the EGR target torque 436based on the air torque request 265 and an EGR torque adjustment 444.For example, the target EGR torque module 440 may set the EGR targettorque 436 equal to the EGR torque adjustment 444 plus the air torquerequest 265.

A second selection module 448 sets the EGR torque adjustment 444 to oneof zero and the I torque adjustment 318 based on a second selectionsignal 452. For example, the second selection module 448 may set the EGRtorque adjustment 444 to zero when the second selection signal 452 is ina first state and set the EGR torque adjustment 444 to the I torqueadjustment 318 when the second selection signal 452 is in a secondstate. The state of the second selection signal 452 may be set, forexample, during the calibration stage of vehicle design. For example,the second selection signal 452 may be set to the first state when theEGR control module 253 can change the target EGR opening 292 at greaterthan a predetermined rate. The second selection signal 452 may be set tothe second state when the EGR control module 253 is limited to changingthe target EGR opening 292 at less than the predetermined rate.

As stated above, the EGR control module 253 (FIG. 2) generates thetarget EGR opening 292 based on the third target APC 291. Morespecifically, the EGR control module 253 may determine a target EGR massflow rate based on the third target APC 291 and the engine speed. TheEGR control module 253 may generate the target EGR mass flow rate, forexample, using the relationship:

M _(EGRT) =f(RPM,APC_(T) _(—) ₃),  (12)

where M_(EGRT) is the mass EGR flow rate, RPM is the engine speed, andAPC_(T) _(—) ₃ is the third target APC 291. This relationship may beembodied as an equation or as a look-up table.

The EGR control module 253 may determine the target EGR opening 292based on the target EGR mass flow rate. The EGR control module 253determines the target EGR opening 292 further based on the target MAP266, an exhaust temperature, and an exhaust pressure. For example, theEGR control module 253 may determine the target EGR opening 292 usingthe relationship:

$\begin{matrix}{{{AREA}_{EGRT} = \frac{M_{EGRT}*\sqrt{R_{GAS}*T_{exh}}}{P_{exh}*{\Phi \left( \frac{{MAP}_{T}}{P_{exh}} \right)}}},} & (13)\end{matrix}$

where AREA_(EGRT) is the target EGR opening 292, M_(EGRT) is the targetEGR mass flow rate, MAP_(T) is the target MAP 266, R_(GAS) is the idealgas constant, T_(exh) is an exhaust temperature, P_(exh) is an exhaustpressure, and φ represents an air density function. As stated above, theEGR actuator module 172 controls the EGR valve 170 based on the targetEGR opening 292.

Referring back to FIG. 3, a target MAP module 332 generates the targetMAP 266 based on the target torque 324, the target spark timing 275, andthe selected intake and exhaust cam phaser angles 330 and 331. Thetarget MAP module 332 generates the target MAP 266 further based on theengine speed, the present air/fuel ratio, the oil temperature, thepresent number of active cylinders, and an estimated torque difference336. Relationship (1) provided above may be inverted and solved todetermine the target MAP 266. For example, the target MAP module 332 maygenerate the target MAP 266 using the relationship:

MAP_(T) =T ⁻¹((T _(T) +f(T _(EST) _(—) _(DIFF))),RPM,S _(T) ,I _(SEL) ,E_(SEL),AF,OT,#),  (14)

where MAP_(T) is the target MAP 266, T_(T) is the target torque 324,T_(EST) _(—) _(DIFF) is the estimated torque difference 336, RPM is theengine speed, S_(T) is the target spark timing 275, I_(SEL) is theselected intake cam phaser angle 330, E_(SEL) is the selected exhaustcam phaser angle 331, AF is the present air/fuel ratio being used by thefuel actuator module 124, OT is the oil temperature, # is the presentnumber of cylinders that are activated, and T⁻¹ denotes inversion ofrelationship (1) above used to relate the MAP 279 to the MAP estimatedtorque 278. In various implementations, the target intake and exhaustcam phaser angles 270 and 271 may be used in place of the selectedintake and exhaust cam phaser angles 330 and 331. This relationship maybe embodied as an equation or as a look-up table. As noted above,generation of the selected intake and exhaust cam phaser angles 330 and331 is discussed further below.

A difference module 340 determines the estimated torque difference 336.The difference module 340 determines the estimated torque difference 336based on a difference between the MAP estimated torque 278 and the firstAPC estimated torque 283. The difference module 340 may also apply afilter to the difference between the MAP estimated torque 278 and thefirst APC estimated torque 283, such as a low pass filter, and outputthe filtered difference as the estimated torque difference 336.

As stated above, the boost control module 248 may generate the targetduty cycle 269 based on the target MAP 266. The boost actuator module164 controls the wastegate 162 (and therefore the turbocharger) based onthe target duty cycle 269.

A first target MAF module 344 generates a first target MAF 348 into theengine 102 based on the first target APC 329. The first target MAFmodule 344 generates the first target MAF 348 further based on theengine speed and the total number of cylinders of the engine 102. Forexample, the first target MAF module 344 may generate the first targetMAF 348 using the relationship:

$\begin{matrix}{{{MAF}_{{T\_}1} = \frac{{APC}_{{T\_}1}*{RPM}}{k_{CYL}}},} & (15)\end{matrix}$

where MAF_(T) _(—) ₁ is the first target MAF 348, APC_(T) _(—) ₁ is thefirst target APC 329, RPM is the engine speed, and k_(CYL) is apredetermined value set based on the total number of cylinders of theengine 102. For example only, k_(CYL) may be approximately 15 for an8-cylinder engine and approximately 30 for a 4-cylinder engine.

Airflow into the engine 102 may vary when one or more cylinders aretransitioned from being activated to being deactivated and when one ormore cylinders are transitioned from being deactivated to beingactivated. Dynamics for airflow into the engine 102 can be representedusing the following first-order relationships:

{dot over (x)}=−ax+bu; and  (16)

y=cx,  (17)

where u is a MAF, x is a MAP, {dot over (x)} is a rate of change of MAP,and y is an APC. The values of a, b, and c can be represented asfollows:

$\begin{matrix}{{a = \frac{\eta*V_{D}*{FF}*{RPM}}{120*V_{MAN}}},} & (18) \\{{b = \frac{R*T_{MAN}}{V_{MAN}}},{and}} & (19) \\{{c = \frac{\eta*V_{D}}{R*T_{MAN}*{Cyls}}},} & (20)\end{matrix}$

where η is a volumetric efficiency of the engine 102, V_(D) is adisplacement volume of the engine 102, FF is a firing fraction of theengine 102, RPM is the engine speed, V_(MAN) is a volume of the intakemanifold 110, R is the Ideal Gas Constant, T_(MAN) is a temperature ofair within the intake manifold 110, and Cyls is the total number ofcylinders of the engine 102. The firing fraction of the engine 102 is avalue between 0 and 1 that corresponds to a ratio of the number ofactivated cylinders to the total number of cylinders of the engine 102.

An example target for the APC to follow for cylinder activation anddeactivation transitions may be expressed as follows:

$\begin{matrix}{{y_{ref} = {{\frac{1}{{T_{ref}*s} + 1}*r} = {\frac{b_{m}}{s + a_{m}}*r}}},} & (21)\end{matrix}$

where T_(Ref) is a target response time constant, r is a reference inputto be followed, and a_(m) and b_(m) are equal to 1/T_(Ref). For exampleonly, the value of T_(Ref) for a desired change of 90% within 80milliseconds (ms) is approximately 0.0364. While example first-orderexamples have been provided, second or higher order relationships may beused. The target response time constant may be a fixed value or avariable value. If a variable value, the target response time constantmay be determined based on, for example, the engine speed, engine load,the temperature of air in the intake manifold 110, and/or one or moreother parameters.

A second target MAF module 460 determines a second target MAF 464 intothe engine 102 based on relationships (16)-(21). More specifically, thesecond target MAF module 460 determines the second target MAF 464 basedon the first target APC 329, the present APC 284, the firing fraction,the temperature within the intake manifold 110, the volumetricefficiency of the engine, and the target response time constant(T_(Ref)). For example, the second target MAF module 460 may determinethe second target MAF 464 using the relationship:

$\begin{matrix}{{{MAF}_{{T\_}2} = {{\frac{b_{m}}{b*c}*{APC}_{{T\_}1}} - {\frac{\left( {a_{m} - a} \right)}{b*c}*{APC}_{P}}}},} & (22)\end{matrix}$

where MAF_(T) _(—) ₂ is the second target MAF 464, APC_(T) _(—) ₁ is thefirst target APC 329, and APC_(P) is the present APC 284. a, a_(m), b,b_(m), and c are described above.

A third selection module 468 sets a selected target MAF 472 to one ofthe first target MAF 348 and the second target MAF 464 based on a thirdselection signal 476. For example, the third selection module 468 mayset the selected target MAF 472 to the first target MAF 348 when thethird selection signal 476 is in a first state and set the selectedtarget MAF 472 to the second target MAF 464 when the third selectionsignal 476 is in a second state.

The cylinder control module 236 may set the state of the third selectionsignal 476. For example, the cylinder control module 236 may set thethird selection signal 476 to the second state a predetermined periodbefore transitioning one or more cylinders from being activated todeactivated and a predetermined period before transitioning one or morecylinders from being deactivated to activated. The cylinder controlmodule 236 may then maintain the third selection signal in the secondstate until that transition is complete. When the transition iscomplete, the cylinder control module 236 may transition the thirdselection signal from the second state to the first state. The cylindercontrol module 236 may maintain the third selection signal in the firststate until one or more cylinders are to be transitioned from activatedto deactivated or vice versa.

In this manner, the second target MAF 464 will be used for apredetermined period before and while one or more cylinders aretransitioned from activated to deactivated or from deactivated toactivated. The first target MAF 348 may be used when the number ofactivated and deactivated cylinders is not changing.

When the third selection signal 476 transitions from the first state tothe second state or vice versa, the third selection module 468 may ratelimit changes in the selected target MAF 472. For example, when thethird selection signal 476 transitions from the first state to thesecond state, the third selection module 468 may adjust the selectedtarget MAF 472 toward the second target MAF 464 by up to a predeterminedamount every predetermined period. When the third selection signal 476transitions from the second state to the first state, the thirdselection module 468 may adjust the selected target MAF 472 toward thefirst target MAF 348 by up to a predetermined amount every predeterminedperiod. In various implementations, the first target MAF module 344 andthe third selection module 468 may be omitted, and the second target MAF464 may be used at all times.

A throttle control module 352 determines the target throttle opening 267for the throttle valve 112 based on the selected target MAF 472. Thethrottle control module 352 determines the target throttle opening 267further based on the target MAP 266, an air temperature, and abarometric pressure. For example, the throttle control module 352 maydetermine the target throttle opening 267 using the relationship:

$\begin{matrix}{{{AREA}_{T} = \frac{{MAF}_{T\_ S}*\sqrt{R_{GAS}*T}}{B*{\Phi \left( \frac{{MAP}_{T}}{B} \right)}}},} & (23)\end{matrix}$

where AREA_(T) is the target throttle opening 267, MAF_(T) _(—) _(S) isthe selected target MAF 472, MAP_(T) is the target MAP 266, R_(GAS) isthe ideal gas constant, T is the air temperature (e.g., ambient orintake), B is the pressure upstream of the throttle valve 112, and φrepresents an air density function. As stated above, the throttleactuator module 116 controls the throttle valve 112 based on the targetthrottle opening 267.

Referring back to the target spark timing 275, the torque relationship(4) provided above may be inverted to solve for a spark APC (not shown).For example, the spark control module 232 may determine the spark APCusing the relationship:

APC_(SPARK) =T ⁻¹(T _(SPARK),RPM,S _(M) ,I _(T) ,E _(T),AF,OT,#)  (24)

where APC_(SPARK) is the spark APC, T_(SPARK) is the spark torquerequest 272, RPM is the engine speed, S_(M) is the present spark timing280 being used by the spark actuator module 126, I_(T) is the targetintake cam phaser angle 270, E_(T) is the target exhaust cam phaserangle 271, AF is the present air/fuel ratio being used by the fuelactuator module 124, OT is the oil temperature, # is the present numberof cylinders that are activated, and T⁻¹ denotes inversion ofrelationship (4) above used to relate the present APC 284 to the firstAPC estimated torque 283. This relationship may be embodied as anequation or as a look-up table.

The spark control module 232 may determine the target spark timing 275based on the spark APC and the engine speed. For example, the sparkcontrol module 232 may determine the target spark timing 275 using therelationship:

S _(T) =f(APC_(SPARK),RPM),  (25)

where S_(T) is the target spark timing 275, APC_(SPARK) is the sparkAPC, and RPM is the engine speed.

A selecting module 356 sets the selected intake and exhaust cam phaserangles 330 and 331 based on either: the measured intake and exhaust camphaser angles 281 and 282; or the target intake and exhaust cam phaserangles 270 and 271, respectively. More specifically, the selectingmodule 356: sets the selected intake cam phaser angle 330 based oneither the measured intake cam phaser angle 281 or the target intake camphaser angle 270; and sets the selected exhaust cam phaser angle 331based on either the measured exhaust cam phaser angle 282 or the targetexhaust cam phaser angle 271.

A selection signal 360 controls whether the selecting module 356 setsthe selected intake and exhaust cam phaser angles 330 and 331 based onthe measured intake and exhaust cam phaser angles 281 and 282 or basedon the target intake and exhaust cam phaser angles 270 and 271. Forexample, the selecting module 356 may set the selected intake andexhaust cam phaser angles 330 and 331 based on the target intake andexhaust cam phaser angles 270 and 271 when the selection signal 360 isin a first state. When the selection signal 360 is in a second state,the selecting module 356 may set the selected intake and exhaust camphaser angles 330 and 331 based on the measured intake and exhaust camphaser angles 281 and 282.

When the selection signal 360 transitions from the first state to thesecond state or vice versa, the selecting module 356 may rate limitchanges in the selected intake and exhaust cam phaser angles 330 and331. For example, when the selection signal 360 transitions from thefirst state to the second state, the selecting module 356 may adjust theselected intake and exhaust cam phaser angles 330 and 331 toward themeasured intake and exhaust cam phaser angles 281 and 282 by up to afirst predetermined amount every predetermined period. When theselection signal 360 transitions from the second state to the firststate, the selecting module 356 may adjust the selected intake andexhaust cam phaser angles 330 and 331 toward the target intake andexhaust cam phaser angles 270 and 271 by up to a second predeterminedamount every predetermined period. The first and second predeterminedamounts may be the same or different.

A selection generation module 364 generates the selection signal 360.The selection generation module 364 sums an APC torque difference 365over a predetermined period (or a predetermined number of samples) todetermine a cumulative difference. A second difference module 366determines the APC torque difference 365. The second difference module366 determines the APC torque difference 365 based on a differencebetween the first APC estimated torque 283 and the second APC estimatedtorque 298. The second difference module 366 may also apply a filter tothe difference between the first APC estimated torque 283 and the secondAPC estimated torque 298, such as a low pass filter, and output thefiltered difference as the APC torque difference 365.

The selection generation module 364 generates the selection signal 360based on the cumulative difference. More specifically, the selectiongeneration module 364 sets the selection signal 360 to the first statewhen the cumulative difference is less than a predetermined value. Whenthe cumulative difference is greater than the predetermined value, theselection generation module 364 may set the selection signal 360 to thesecond state.

In this manner the selecting module 356 sets the selected intake andexhaust cam phaser angles 330 and 331 based on the target intake andexhaust cam phaser angles 270 and 271 when the cumulative difference isless than the predetermined value. When the cumulative difference isgreater than the predetermined value, the selecting module 356 may setthe selected intake and exhaust cam phaser angles 330 and 331 based onthe measured intake and exhaust cam phaser angles 281 and 282. This mayensure that use of the target intake and exhaust cam phaser angles 270and 271 is limited to times when the target intake and exhaust camphaser angles 270 and 271 are accurate, as indicated by the cumulativedifference being less than the predetermined value.

Referring now to FIG. 5, a flowchart depicting an example method ofcontrolling the throttle valve 112 is presented. Control may begin with504 where the torque requesting module 224 generates the air torquerequest 265. The delay and rate limit module 302 updates the shaped airtorque request 303 at 508. The delay and rate limit module 302 receivesthe air torque request 265 and stores the air torque request 265 for thedelay period. The delay and rate limit module 302 adjusts the shaped airtorque request 303 toward a stored air torque request by up to thepredetermined amount. The delay period and the predetermined amount maybe determined, for example, based on the EGR value and/or the enginespeed.

The torque error module 304 generates the torque error 308 at 512. Thetorque error module 304 determines the torque error 308 based on adifference between the shaped air torque request 303 and the first APCestimated torque 283. The adjustment module 312 determines the P torqueadjustment, the I torque adjustment 318, and the torque adjustment 316at 516 based on the torque error 308. As discussed above in conjunctionwith relationship (6), the adjustment module 312 may determine the Ptorque adjustment based on a product of the proportional gain (KP) andthe torque error 308 and determine the I torque adjustment 318 based ona product of the torque error 308 and an integral gain (KI). Theadjustment module 312 may set the torque adjustment 316 equal to the Itorque adjustment 318 plus the P torque adjustment.

At 520, the target determination module 320 generates the target torque324. The target determination module 320 determines the target torque324 based on the torque adjustment 316 and the shaped air torque request303, as discussed above. At 524, the first APC determination module 404determines the first target APC 329, the first target MAF module 344determines the first target MAF 348, the second target MAF module 460determines the second target MAF 464, and the target MAP module 332determines the target MAP 266.

The first APC determination module 404 determines the first target APC329 based on the target torque 324, as discussed above. The first targetMAF module 344 determines the first target MAF 348 based on the firsttarget APC 329, as discussed above. The target MAP module 332 determinesthe target MAP 266 based on the target torque 324, as discussed above.The second target MAF module 460 determines the second target MAF 464based on the first target APC 329, the present APC 284, the firingfraction, the temperature within the intake manifold 110, the volumetricefficiency of the engine 102, and the target response time constant(TRef), as discussed above.

At 528, the cylinder control module 236 may determine whether one ormore cylinders should be transitioned from activated to deactivated orfrom deactivated to activated. For example, the cylinder control module236 may activate one or more cylinders when a torque request increasesand may deactivate one or more cylinders when a torque requestdecreases. If 528 is true, the third selection module 468 may set theselected target MAF 472 to or based on the second target MAF 464 at 532,and control continues with 540. If 528 is false, the third selectionmodule 468 may set the selected target MAF 472 to or based on the firsttarget MAF at 536, and control continues with 540.

At 540, the throttle control module 352 generates the target throttleopening 267 based on the selected target MAF 472 and the target MAP 266,as discussed above. In various implementations, 528-536 may be omitted,and the throttle control module 352 may generate the target throttleopening 267 based on the second target MAF 464 and the target MAP 266.At 544, the throttle actuator module 116 selectively adjusts thethrottle valve 112 based on the target throttle opening 267. Control maythen end. While control is shown and discussed as ending, FIG. 5 may beillustrative of one control loop, and control loops may be executed at apredetermined rate.

The foregoing description is merely illustrative in nature and is in noway intended to limit the disclosure, its application, or uses. Thebroad teachings of the disclosure can be implemented in a variety offorms. Therefore, while this disclosure includes particular examples,the true scope of the disclosure should not be so limited since othermodifications will become apparent upon a study of the drawings, thespecification, and the following claims. As used herein, the phrase atleast one of A, B, and C should be construed to mean a logical (A or Bor C), using a non-exclusive logical OR. It should be understood thatone or more steps within a method may be executed in different order (orconcurrently) without altering the principles of the present disclosure.

In this application, including the definitions below, the term modulemay be replaced with the term circuit. The term module may refer to, bepart of, or include an Application Specific Integrated Circuit (ASIC); adigital, analog, or mixed analog/digital discrete circuit; a digital,analog, or mixed analog/digital integrated circuit; a combinationallogic circuit; a field programmable gate array (FPGA); a processor(shared, dedicated, or group) that executes code; memory (shared,dedicated, or group) that stores code executed by a processor; othersuitable hardware components that provide the described functionality;or a combination of some or all of the above, such as in asystem-on-chip.

The term code, as used above, may include software, firmware, and/ormicrocode, and may refer to programs, routines, functions, classes,and/or objects. The term shared processor encompasses a single processorthat executes some or all code from multiple modules. The term groupprocessor encompasses a processor that, in combination with additionalprocessors, executes some or all code from one or more modules. The termshared memory encompasses a single memory that stores some or all codefrom multiple modules. The term group memory encompasses a memory that,in combination with additional memories, stores some or all code fromone or more modules. The term memory may be a subset of the termcomputer-readable medium. The term computer-readable medium does notencompass transitory electrical and electromagnetic signals propagatingthrough a medium, and may therefore be considered tangible andnon-transitory. Non-limiting examples of a non-transitory tangiblecomputer readable medium include nonvolatile memory, volatile memory,magnetic storage, and optical storage.

The apparatuses and methods described in this application may bepartially or fully implemented by one or more computer programs executedby one or more processors. The computer programs includeprocessor-executable instructions that are stored on at least onenon-transitory tangible computer readable medium. The computer programsmay also include and/or rely on stored data.

What is claimed is:
 1. An engine control system for a vehicle,comprising: a target torque module that determines a target torqueoutput of an engine based on at least one driver input; a target air percylinder (APC) module that determines a target APC for the engine basedon the target torque; a target mass airflow (MAF) module that determinesa target MAF through a throttle valve of the engine based on the targetAPC, a number of activated cylinders of the engine, and a total numberof cylinders of the engine; and a throttle control module thatdetermines a target throttle opening based on the target MAF and thatcontrols opening of the throttle valve based on the target throttleopening.
 2. The engine control system of claim 1 wherein the target MAFmodule determines the target MAF further based on an APC of the engine,a temperature of air within an intake manifold of the engine, avolumetric efficiency of the engine, and a predetermined response timevalue.
 3. The engine control system of claim 2 wherein the target MAFmodule determines the target MAF using one of a function and a mappingthat relates the target APC, the number of activated cylinders, thetotal number of cylinders, the APC, the temperature, the volumetricefficiency, and the predetermined response time value to the target MAF.4. The engine control system of claim 1 further comprising: a secondtarget MAF module that determines a second target MAF through thethrottle valve based on the target APC; and a selection module thatselects one of the target MAF and the second target MAF and that sets aselected target MAF based on the selected one of the target MAF and thesecond target MAF, wherein the throttle control module determines thetarget throttle opening based on the selected target MAF.
 5. The enginecontrol system of claim 4 wherein the selection module selects thetarget MAF when at least one cylinder of the engine is transitioned fromactivated to deactivated.
 6. The engine control system of claim 5wherein the selection module selects the target MAF for a predeterminedperiod before the at least one cylinder of the engine is transitionedfrom activated to deactivated.
 7. The engine control system of claim 4wherein the selection module selects the target MAF when at least onecylinder of the engine is transitioned from deactivated to activated. 8.The engine control system of claim 7 wherein the selection moduleselects the target MAF for a predetermined period before the at leastone cylinder of the engine is transitioned from deactivated toactivated.
 9. The engine control system of claim 4 wherein the selectionmodule selects the second target MAF when zero cylinders of the engineare transitioned from deactivated to activated and zero cylinders of theengine are transitioned from activated to deactivated.
 10. The enginecontrol system of claim 1 wherein the throttle control module determinesthe target throttle opening further based on a target intake manifoldpressure.
 11. An engine control method comprising: determining a targettorque output of an engine based on at least one driver input;determining a target air per cylinder (APC) for the engine based on thetarget torque; determining a target mass airflow (MAF) through athrottle valve of the engine based on the target APC, a number ofactivated cylinders of the engine, and a total number of cylinders ofthe engine; determining a target throttle opening based on the targetMAF; and controlling opening of the throttle valve based on the targetthrottle opening.
 12. The engine control method of claim 11 furthercomprising determining the target MAF further based on an APC of theengine, a temperature of air within an intake manifold of the engine, avolumetric efficiency of the engine, and a predetermined response timevalue.
 13. The engine control method of claim 12 further comprisingdetermining the target MAF using one of a function and a mapping thatrelates the target APC, the number of activated cylinders, the totalnumber of cylinders, the APC, the temperature, the volumetricefficiency, and the predetermined response time value to the target MAF.14. The engine control method of claim 11 further comprising:determining a second target MAF through the throttle valve based on thetarget APC; selecting one of the target MAF and the second target MAF;setting a selected target MAF based on the selected one of the targetMAF and the second target MAF; and determining the target throttleopening based on the selected target MAF.
 15. The engine control methodof claim 14 further comprising selecting the target MAF when at leastone cylinder of the engine is transitioned from activated todeactivated.
 16. The engine control method of claim 15 furthercomprising selecting the target MAF for a predetermined period beforethe at least one cylinder of the engine is transitioned from activatedto deactivated.
 17. The engine control method of claim 14 furthercomprising selecting the target MAF when at least one cylinder of theengine is transitioned from deactivated to activated.
 18. The enginecontrol method of claim 17 further comprising selecting the target MAFfor a predetermined period before the at least one cylinder of theengine is transitioned from deactivated to activated.
 19. The enginecontrol method of claim 14 further comprising selecting the secondtarget MAF when zero cylinders of the engine are transitioned fromdeactivated to activated and zero cylinders of the engine aretransitioned from activated to deactivated.
 20. The engine controlmethod of claim 11 further comprising determining the target throttleopening further based on a target intake manifold pressure.